Two SA cold case murders thought linked

The disappearance of two South Australian men, both presumed murdered, are now believed to be linked but finding their bodies has turned into a "needle-in-a-haystack" exercise.

Russell Bradshaw, 35, went missing in 1992 and Damien Cauchi, 21, in 1998 with their remains thought to be in the Murray Mallee region.

Acting Senior Sergeant Rod Huppatz says information suggests Mr Cauchi had been associating with two suspects in the disappearance of Mr Bradshaw.

"We believe it's a possibility that Mr Cauchi went missing because of his association with that person and possibly because of some knowledge he had regarding what happened to Mr Bradshaw," Sgt Huppatz said.

"However, there is no suggestion that Mr Cauchi was involved in the murder of Mr Bradshaw."

Police have searched for the two bodies on several occasions without success. They believe the two men were dumped close to each other, somewhere near Karoonda, but not in the same location.

"It's a very expansive area and unfortunately it's needle-in-a-haystack stuff," Sgt Huppatz said.